Abstract

Many forests and their associated water resources are at increasing risk from large and severe wildfires due tohigh fuel accumulations and climate change. Extensive fuel treatments are being proposed, but it is not clear where suchtreatments should be focussed. The goals of this project were to: (1) predict potential post-fire erosion rates for forests andshrublands in the western United States to help prioritise fuel treatments; and (2) assess model sensitivity and accuracy.Post-fire ground cover was predicted using historical fire weather data and the First Order Fire Effects Model. Parameterfiles from the Disturbed Water Erosion Prediction Project (WEPP) were combined with GeoWEPP to predict post-fireerosion at the hillslope scale. Predicted median annual erosion rates were 0.1�2 Mg ha1 year1 for most of theintermountain west, ,10�40 Mg ha1 year1 for wetter areas along the Pacific Coast and up to 100 Mg ha1 year1 fornorth-western California. Sensitivity analyses showed the predicted erosion rates were predominantly controlled by theamount of precipitation rather than surface cover. The limited validation dataset showed a reasonable correlation betweenpredicted and measured erosion rates (R2 � 0.61), although predictions were much less than measured values. Our resultsdemonstrate the feasibility of predicting post-fire erosion rates on a large scale. The validation and sensitivity analysisindicated that the predictions are most useful for prioritising fuel reduction treatments on a local rather than interregionalscale, and they also helped identify model improvements and research needs.